596 CROSS, IDDINGS, PIRSSON, WASHINGTON 



of CI yielding a notable amount of sodalite) , and because, so 

 far as has been observed, or seems a priori possible, the minerals 

 of the sodalite group are only present in the sodic or sodipotas- 

 sic Subrangs of Classes I, II and III. It may be pointed out 

 that the sodalite minerals are also characterized by the presence 

 of more Na 3 than A1 2 3 . 



The lenads to be contrasted are the simple silicates, nephelite 

 and leucite, on the one hand, and the more complex silicates, 

 sodalite and noselite, on the other. The former may be desig- 

 nated by the symbols ne and lc, and the latter by so and no, 

 and the mnemonic syallables indicating these subgroups are nel 

 and son. 



The division will be needed only in Orders 6, 7, 8 and 9, 

 which contain notable amounts of lenads, and will be five- 

 fold in the sodipotassic, dosodic and persodic Subrangs of the 

 peralkalic, domalkalic and alkalicalcic Rangs. 



ne, lc 7 

 Section 1 : — < - , pernehc. 



7 S 

 Section 2 : — < - > - , donelic. 



1 3 



C "2 



Section 3 : ""' < - > - , sonnelic. 

 3 5 



•2 1 

 Section 4 : - — ^r: < - > - > dosonic. 



5 7 



Section 5 : - < - , personic. 



so, no 7 



In the dopotassic Subrangs of the Rangs just mentioned, and 

 in the sodipotassic and presodic Subrangs of the docalcic Rangs, 

 the division will be threefold : 



ne > l c 5 i- 



Section 1 : > - , prenehc. 



so, no 3 



lc ne ^ % 



Section 2 : — < - > - , sonnelic. 



so, no 3 5 



ne lc ~x 

 Section -z : — - — < - , presonic. 



so, no 5 



